1 files changed, 53 insertions, 6 deletions
diff --git a/vendor/github.com/hashicorp/terraform/vendor/github.com/mitchellh/cli/ui_mock.go b/vendor/github.com/hashicorp/terraform/vendor/github.com/mitchellh/cli/ui_mock.go
index c4677285..0bfe0a19 100644
--- a/vendor/github.com/hashicorp/terraform/vendor/github.com/mitchellh/cli/ui_mock.go
+++ b/vendor/github.com/hashicorp/terraform/vendor/github.com/mitchellh/cli/ui_mock.go
@@ -7,12 +7,25 @@ import (
 	"sync"
 )
 
-// MockUi is a mock UI that is used for tests and is exported publicly for
-// use in external tests if needed as well.
+// NewMockUi returns a fully initialized MockUi instance
+// which is safe for concurrent use.
+func NewMockUi() *MockUi {
+	m := new(MockUi)
+	m.once.Do(m.init)
+	return m
+}
+
+// MockUi is a mock UI that is used for tests and is exported publicly
+// for use in external tests if needed as well. Do not instantite this
+// directly since the buffers will be initialized on the first write. If
+// there is no write then you will get a nil panic. Please use the
+// NewMockUi() constructor function instead. You can fix your code with
+//
+//  sed -i -e 's/new(cli.MockUi)/cli.NewMockUi()/g' *_test.go
 type MockUi struct {
 	InputReader  io.Reader
-	ErrorWriter  *bytes.Buffer
-	OutputWriter *bytes.Buffer
+	ErrorWriter  *syncBuffer
+	OutputWriter *syncBuffer
 
 	once sync.Once
 }
@@ -59,6 +72,40 @@ func (u *MockUi) Warn(message string) {
 }
 
 func (u *MockUi) init() {
-	u.ErrorWriter = new(bytes.Buffer)
-	u.OutputWriter = new(bytes.Buffer)
+	u.ErrorWriter = new(syncBuffer)
+	u.OutputWriter = new(syncBuffer)
+}
+
+type syncBuffer struct {
+	sync.RWMutex
+	b bytes.Buffer
+}
+
+func (b *syncBuffer) Write(data []byte) (int, error) {
+	b.Lock()
+	defer b.Unlock()
+	return b.b.Write(data)
+}
+
+func (b *syncBuffer) Read(data []byte) (int, error) {
+	b.RLock()
+	defer b.RUnlock()
+	return b.b.Read(data)
+}
+
+func (b *syncBuffer) Reset() {
+	b.Lock()
+	b.b.Reset()
+	b.Unlock()
+}
+
+func (b *syncBuffer) String() string {
+	return string(b.Bytes())
+}
+
+func (b *syncBuffer) Bytes() []byte {
+	b.RLock()
+	data := b.b.Bytes()
+	b.RUnlock()
+	return data
 }